Mars Kicks Up the Dust
as
It Makes Closest Approach to Earth

NASA's
Hubble Space Telescope snapped this picture
of Mars on October 28, within a day of its
closest approach to Earth on the night of
October 29. A large regional dust storm
appears as the brighter, redder cloudy region
in the middle of the planet's disk.

This storm, which measures 930 miles (1500
kms) has been churning in the planet's equatorial
regions for several weeks now, and it is
likely responsible for the reddish, dusty
haze and other dust clouds seen across this
hemisphere of the planet. Hubble's Advanced
Camera
for Surveys High Resolution Imager took
this image when the red planet was 43 million
miles (69 million km) from Earth. Mars won't
be this close again to Earth until 2018.

Mars is now in its warmest months, closest
to the Sun in its orbit, resulting in a
smaller than normal south polar ice cap
which has largely sublimated with the approaching
summer.The occurrence of
the dust storm in close proximity to the
NASA Mars Exploration Rover Opportunity's
landing site in Meridiani Planum has the
potential to cause problems for the rover.
Specifically, if the dust in the atmosphere
gets thick enough it could block some of
the sunlight needed to keep the rover operating
at full capacity.

In 2005, the Mars closest approach and opposition occurred within a week of each other. On October 28/29 (depending on what time zone one lived), Mars was the closest it has been in the last two years, reaching a distance of only 43 million miles from Earth. On this date, the Mars, Earth, Sun angle was almost lined up but not quite, resulting in a slight shadow on the eastern edge of Mars. On November 7, the Mars, Earth, Sun angle was perfectly aligned, and Mars was in opposition with the Sun as seen from Earth. This resulted in a perfect globe of Mars viewed from Earth and from the Hubble Space Telescope on November 8. Two different detectors were used on the two dates that Hubble opbserved the Red Planet, the first image being taken on October 28 with the Advanced Camera for Surveys High Resolution Channel, and the second image on November 8 with the Wide Field Planetary Camera 2. Slightly different filters on the two detectors pick up subtly different features on the Martian surface and in the Martian atmosphere. More cloud structure appears in the opposition image, making the planet appear somewhat wider at the equator.

Click on
the illustration to learn more about the
the past six Mars oppositions with Earth.

The Hubble Heritage team wishes to thank Jim Bell (Cornell University) and Mike Wolff (Space Science Institute) for their support with these Mars observations.